Merge branch 'main' into fix-build-update

CONTRIBUTING.md

@@ -111,7 +111,7 @@ directory.
 
 Every Ziglings exercise contains mistakes on purpose.
 To keep our automated tests happy, each exercise also
-has a patch in `patches/healed` that “heals” it.
+has a patch in `patches/patches` that “heals” it.
 
 When you change an exercise, you will usually need to update
 its patch too. That’s where our little helper Gollum comes in:

build.zig

@@ -30,7 +30,7 @@ comptime {
     }
 }
 
-// Elrond owns the entire Ziglings logic now!
+// Elrond the Wise owns the entire Ziglings logic now!
 // build.zig only builds it and forwards the chosen options as CLI flags.
 // Building just this one Run step keeps the build output readable and lets
 // Elrond iterate without the configure-phase cache getting in the way.
@@ -46,6 +46,7 @@ pub fn build(b: *Build) !void {
     const rand = b.option(bool, "random", "Select random exercise");
     const start = b.option(usize, "s", "Start at exercise");
     const reset = b.option(bool, "reset", "Reset exercise progress");
+    const logo = b.option(bool, "logo", "Display Ziglings logo");
 
     const sep = std.fs.path.sep_str;
     const healed_path = if (override_healed_path) |path|
@@ -57,7 +58,7 @@ pub fn build(b: *Build) !void {
     const elrond = b.addExecutable(.{
         .name = "elrond",
         .root_module = b.createModule(.{
-            .root_source_file = b.path("src/elrond.zig"),
+            .root_source_file = b.path("rivendell/elrond.zig"),
             .target = b.graph.host,
         }),
     });
@@ -87,6 +88,8 @@ pub fn build(b: *Build) !void {
         run.addArg("--random");
     } else if (start) |s| {
         run.addArg(b.fmt("--start={d}", .{s}));
+    } else if (logo) |_| {
+        run.addArg("--logo");
     }
 
     const ziglings_step = b.step("ziglings", "Run ziglings");

exercises/028_defer2.zig

@@ -10,6 +10,8 @@ pub fn main() void {
     for (animals) |a| printAnimal(a);
 
     std.debug.print("done.\n", .{});
+
+    std.debug.print("Answer to everything? {d}\n", .{calculateTheUltimateQuestionOfLife()});
 }
 
 // This function is _supposed_ to print an animal name in parentheses
@@ -35,3 +37,24 @@ fn printAnimal(animal: u8) void {
 
     std.debug.print("Unknown", .{});
 }
+
+// This function is supposed to calculate the answer to the
+// ultimate question of life, the universe, and everything,
+// but it needs to be deferred as far in the future as possible,
+// in order to gather more data.
+//
+// When there are multiple defers in a single block, they are executed in reverse order.
+// This example might seem silly, but it's important to know when e.g.
+// deinitializing containers whose elements need to be deinitialized first.
+fn calculateTheUltimateQuestionOfLife() u32 {
+    var x: u32 = 100;
+
+    // Try reordering the statements to get the answer 42
+    {
+        defer x = x / 10;
+        defer x = x + 11;
+        defer x = x * 2;
+    }
+
+    return x;
+}

exercises/110_files2.zig

@@ -36,10 +36,10 @@ pub fn main(init: std.process.Init) !void {
     const file = try output_dir.openFile(io, "zigling.txt", .{});
     defer file.close(io);
 
-    // initialize an array of u8 with all letter 'A'
+    // initialize an array of u8 entirely with the letter 'A'
     // we need to pick the size of the array, 64 seems like a good number
-    // fix the initialization below
+    // do you remember the array repetition function?
-    var content = ['A']*64;
+    var content: ??? = ???('A');
     // this should print out : `AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA`
     std.debug.print("{s}\n", .{content});
 

patches/patches/028_defer2.patch

@@ -1,6 +1,6 @@
---- exercises/028_defer2.zig	2023-10-03 22:15:22.122241138 +0200
+--- exercises/028_defer2.zig	2026-06-02 06:08:12.713672612 +0200
-+++ answers/028_defer2.zig	2023-10-05 20:04:06.966098530 +0200
++++ answers/028_defer2.zig	2026-06-02 06:08:43.262234023 +0200
-@@ -18,7 +18,7 @@
+@@ -20,7 +20,7 @@
  fn printAnimal(animal: u8) void {
      std.debug.print("(", .{});
  
@@ -9,3 +9,15 @@
  
      if (animal == 'g') {
          std.debug.print("Goat", .{});
+@@ -51,9 +51,9 @@
+ 
+     // Try reordering the statements to get the answer 42
+     {
+-        defer x = x / 10;
+-        defer x = x + 11;
+         defer x = x * 2;
++        defer x = x + 11;
++        defer x = x / 10;
+     }
+ 
+     return x;

patches/patches/110_files2.patch

@@ -1,10 +1,10 @@
---- exercises/110_files2.zig	2026-05-04 17:08:38.913033915 +0200
+--- exercises/110_files2.zig	2026-05-31 14:54:55.061019159 +0200
-+++ answers/110_files2.zig	2026-05-04 17:08:37.112995948 +0200
++++ answers/110_files2.zig	2026-05-31 14:54:42.655691238 +0200
 @@ -39,7 +39,7 @@
-     // initialize an array of u8 with all letter 'A'
+     // initialize an array of u8 entirely with the letter 'A'
      // we need to pick the size of the array, 64 seems like a good number
-     // fix the initialization below
+     // do you remember the array repetition function?
--    var content = ['A']*64;
+-    var content: ??? = ???('A');
 +    var content: [64]u8 = @splat('A');
      // this should print out : `AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA`
      std.debug.print("{s}\n", .{content});

rivendell/elrond.zig

@@ -1,4 +1,8 @@
-// Elrond: Ziglings' exercise checker and guide.
+//
+//     "You have a long way to go,
+//      and the path is not easy."
+//            Elrond, The Hobbit or The Fellowship of the Ring
+//
 //
 // In the reworked Zig build system (configurer/maker split) a build Step no
 // longer carries a `makeFn`, and the configure phase is cached and not re-run
@@ -33,10 +37,9 @@ pub const logo =
     \\
 ;
 
-// How Elrond was invoked.
+// How Elrond was called.
 const Mode = enum {
-    // `zig build`: iterate from after the last solved exercise to the first
+    // `zig build`: iterate from after the last solved exercise to the first unsolved one (or the end).
-    // unsolved one (or the end).
     normal,
     // `zig build -Dn=n`: check exactly one exercise.
     named,
@@ -57,8 +60,7 @@ pub const Exercise = struct {
     // main_file must have the format key_name.zig.
     main_file: []const u8,
 
-    // Desired output. A program passes if its output, excluding trailing
+    // Desired output. A program passes if its output, excluding trailing whitespace, equals this string.
-    // whitespace, equals this string.
     output: []const u8,
 
     // Optional hint shown if the program does not succeed.
@@ -86,11 +88,9 @@ pub const Exercise = struct {
         return std.fs.path.stem(self.main_file);
     }
 
-    // Key of the main file: the string before the '_' with zero padding
+    // Key of the main file: the string before the '_' with zero padding removed. "001_hello.zig" -> "1".
-    // removed. "001_hello.zig" -> "1".
     pub fn key(self: Exercise) []const u8 {
-        const end_index = std.mem.indexOfScalar(u8, self.main_file, '_') orelse
+        const end_index = std.mem.indexOfScalar(u8, self.main_file, '_') orelse unreachable;
-            unreachable;
         var start_index: usize = 0;
         while (self.main_file[start_index] == '0') start_index += 1;
         return self.main_file[start_index..end_index];
@@ -102,11 +102,13 @@ pub const Exercise = struct {
     }
 };
 
+// Ansi colors.
 var use_color_escapes = false;
 var red_text: []const u8 = "";
 var red_bold_text: []const u8 = "";
 var red_dim_text: []const u8 = "";
 var green_text: []const u8 = "";
+var yellow_text: []const u8 = "";
 var bold_text: []const u8 = "";
 var reset_text: []const u8 = "";
 
@@ -126,6 +128,7 @@ fn setupColors(io: std.Io) void {
         red_bold_text = "\x1b[31;1m";
         red_dim_text = "\x1b[31;2m";
         green_text = "\x1b[32m";
+        yellow_text = "\x1b[33m";
         bold_text = "\x1b[1m";
         reset_text = "\x1b[0m";
     }
@@ -133,9 +136,9 @@ fn setupColors(io: std.Io) void {
 
 pub fn main(init: std.process.Init) !void {
     const io = init.io;
-    const gpa = init.arena.allocator();
+    const arena = init.arena.allocator();
 
-    const args = try init.minimal.args.toSlice(gpa);
+    const args = try init.minimal.args.toSlice(arena);
 
     setupColors(io);
 
@@ -150,17 +153,7 @@ pub fn main(init: std.process.Init) !void {
     for (1..args.len) |n| {
         const arg = args[n];
         if (std.mem.eql(u8, arg, "--logo")) {
-            print("{s}", .{logo});
+            print("{s}{s}{s}", .{ yellow_text, logo, reset_text });
-            return;
-        } else if (std.mem.eql(u8, arg, "--reset")) {
-            std.Io.Dir.cwd().deleteFile(io, progress_filename) catch |err| switch (err) {
-                error.FileNotFound => {},
-                else => {
-                    print("Unable to remove progress file: {}\n", .{err});
-                    std.process.exit(1);
-                },
-            };
-            print("Progress reset, {s} removed.\n", .{progress_filename});
             return;
         } else if (prefix(arg, "--zig=")) |v| {
             zig_exe = v;
@@ -188,7 +181,7 @@ pub fn main(init: std.process.Init) !void {
 
     print("{s}", .{logo});
 
-    const ctx: Context = .{ .io = io, .gpa = gpa, .zig_exe = zig_exe, .work_path = work_path };
+    const ctx: Context = .{ .io = io, .arena = arena, .zig_exe = zig_exe, .work_path = work_path };
 
     switch (mode) {
         .named => {
@@ -220,7 +213,7 @@ pub fn main(init: std.process.Init) !void {
         },
         .normal => {
             // Start after the last solved exercise recorded in .progress.txt.
-            const solved = readProgress(io, gpa);
+            const solved = readProgress(io, arena);
             var start_index: usize = 0;
             for (exercises, 0..) |ex, idx| {
                 if (solved < ex.number()) {
@@ -245,15 +238,15 @@ fn prefix(arg: []const u8, pre: []const u8) ?[]const u8 {
 // Shared, read-only run context threaded through the helpers.
 const Context = struct {
     io: std.Io,
-    gpa: std.mem.Allocator,
+    arena: std.mem.Allocator,
     zig_exe: []const u8,
     work_path: []const u8,
 };
 
 const Error = error{Failed};
 
-// Iterates exercises from `start_index` to the end, stopping at the first
+// Iterates exercises from `start_index` to the end, stopping at the first failure.
-// failure. Progress is written after each passed exercise.
+// Progress is written after each passed exercise.
 fn iterateFrom(ctx: Context, start_index: usize) Error!void {
     for (exercises[start_index..]) |ex| {
         try runOne(ctx, ex, .normal);
@@ -284,12 +277,12 @@ fn runOne(ctx: Context, ex: Exercise, mode: Mode) Error!void {
         },
     }
 
-    writeProgress(ctx.io, ctx.gpa, ex.number()) catch {};
+    writeProgress(ctx.io, ctx.arena, ex.number()) catch {};
 }
 
 fn hintAndHelp(ex: Exercise, mode: Mode) void {
     if (ex.hint) |hint|
-        print("\n{s}Ziglings hint: {s}{s}", .{ bold_text, hint, reset_text });
+        print("\n{s}{s}Ziglings hint: {s}{s}", .{ bold_text, green_text, hint, reset_text });
     help(ex, mode);
 }
 
@@ -313,24 +306,22 @@ fn printProgress(num: usize, max: usize) void {
 
 fn runExe(ctx: Context, ex: Exercise) !void {
     const io = ctx.io;
-    const gpa = ctx.gpa;
+    const arena = ctx.arena;
     print("Compiling {s}...\n", .{ex.main_file});
 
-    const path = std.fs.path.join(gpa, &.{ ctx.work_path, ex.main_file }) catch
+    const path = std.fs.path.join(arena, &.{ ctx.work_path, ex.main_file }) catch @panic("OOM");
-        @panic("OOM");
 
-    var argv = std.ArrayList([]const u8).initCapacity(gpa, 8) catch @panic("OOM");
+    var argv = std.ArrayList([]const u8).initCapacity(arena, 8) catch @panic("OOM");
-    defer argv.deinit(gpa);
+    argv.append(arena, ctx.zig_exe) catch @panic("OOM");
-    argv.append(gpa, ctx.zig_exe) catch @panic("OOM");
+    argv.append(arena, "run") catch @panic("OOM");
-    argv.append(gpa, "run") catch @panic("OOM");
     if (ex.link_libc) {
-        argv.append(gpa, "-lc") catch @panic("OOM");
+        argv.append(arena, "-lc") catch @panic("OOM");
-        argv.append(gpa, "-fllvm") catch @panic("OOM");
+        argv.append(arena, "-fllvm") catch @panic("OOM");
     }
-    argv.append(gpa, path) catch @panic("OOM");
+    argv.append(arena, path) catch @panic("OOM");
 
     // `zig run` compiles and runs in one step using Zig's own cache.
-    const result = Process.run(gpa, io, .{
+    const result = Process.run(arena, io, .{
         .argv = argv.items,
         .stdout_limit = .limited(1024 * 1024),
         .stderr_limit = .limited(1024 * 1024),
@@ -344,28 +335,27 @@ fn runExe(ctx: Context, ex: Exercise) !void {
     resetLine();
     print("Checking {s}...\n", .{ex.main_file});
 
-    return checkOutput(io, gpa, ex, result);
+    return checkOutput(io, arena, ex, result);
 }
 
 fn runTest(ctx: Context, ex: Exercise) !void {
     const io = ctx.io;
-    const gpa = ctx.gpa;
+    const arena = ctx.arena;
     print("Compiling {s}...\n", .{ex.main_file});
 
-    const path = std.fs.path.join(gpa, &.{ ctx.work_path, ex.main_file }) catch
+    const path = std.fs.path.join(arena, &.{ ctx.work_path, ex.main_file }) catch
         @panic("OOM");
 
-    var argv = std.ArrayList([]const u8).initCapacity(gpa, 8) catch @panic("OOM");
+    var argv = std.ArrayList([]const u8).initCapacity(arena, 8) catch @panic("OOM");
-    defer argv.deinit(gpa);
+    argv.append(arena, ctx.zig_exe) catch @panic("OOM");
-    argv.append(gpa, ctx.zig_exe) catch @panic("OOM");
+    argv.append(arena, "test") catch @panic("OOM");
-    argv.append(gpa, "test") catch @panic("OOM");
     if (ex.link_libc) {
-        argv.append(gpa, "-lc") catch @panic("OOM");
+        argv.append(arena, "-lc") catch @panic("OOM");
-        argv.append(gpa, "-fllvm") catch @panic("OOM");
+        argv.append(arena, "-fllvm") catch @panic("OOM");
     }
-    argv.append(gpa, path) catch @panic("OOM");
+    argv.append(arena, path) catch @panic("OOM");
 
-    const result = Process.run(gpa, io, .{
+    const result = Process.run(arena, io, .{
         .argv = argv.items,
         .stdout_limit = .limited(1024 * 1024),
         .stderr_limit = .limited(1024 * 1024),
@@ -382,7 +372,7 @@ fn runTest(ctx: Context, ex: Exercise) !void {
     return checkTest(ex, result);
 }
 
-fn checkOutput(io: std.Io, gpa: std.mem.Allocator, ex: Exercise, result: Process.RunResult) !void {
+fn checkOutput(io: std.Io, arena: std.mem.Allocator, ex: Exercise, result: Process.RunResult) !void {
     switch (result.term) {
         .exited => |code| if (code != 0) {
             // `zig run` puts both compile errors and runtime panics on stderr;
@@ -400,7 +390,7 @@ fn checkOutput(io: std.Io, gpa: std.mem.Allocator, ex: Exercise, result: Process
     }
 
     const raw_output = if (ex.check_stdout) result.stdout else result.stderr;
-    const output = trimLines(gpa, raw_output) catch @panic("OOM");
+    const output = trimLines(arena, raw_output) catch @panic("OOM");
 
     var exercise_output = ex.output;
     if (ex.timestamp) {
@@ -477,28 +467,27 @@ fn resetLine() void {
 }
 
 // Removes trailing whitespace per line and any trailing LF at the end.
-fn trimLines(gpa: std.mem.Allocator, buf: []const u8) ![]const u8 {
+fn trimLines(arena: std.mem.Allocator, buf: []const u8) ![]const u8 {
-    var list = try std.ArrayList(u8).initCapacity(gpa, buf.len);
+    var list = try std.ArrayList(u8).initCapacity(arena, buf.len);
-    errdefer list.deinit(gpa);
 
     var iter = std.mem.splitSequence(u8, buf, " \n");
     while (iter.next()) |line| {
         const data = std.mem.trimEnd(u8, line, " \r");
-        try list.appendSlice(gpa, data);
+        try list.appendSlice(arena, data);
-        try list.append(gpa, '\n');
+        try list.append(arena, '\n');
     }
-    const result = try list.toOwnedSlice(gpa);
+    const result = try list.toOwnedSlice(arena);
     return std.mem.trimEnd(u8, result, "\n");
 }
 
 // Reads the last solved exercise number from .progress.txt; 0 if absent.
-fn readProgress(io: std.Io, gpa: std.mem.Allocator) u32 {
+fn readProgress(io: std.Io, arena: std.mem.Allocator) u32 {
     const file = std.Io.Dir.cwd().openFile(io, progress_filename, .{}) catch return 0;
     defer file.close(io);
 
     const size = file.length(io) catch return 0;
     if (size == 0) return 0;
-    const contents = gpa.alloc(u8, size) catch return 0;
+    const contents = arena.alloc(u8, size) catch return 0;
     var file_buffer: [1024]u8 = undefined;
     var reader = file.reader(io, &file_buffer);
     const n = reader.interface.readSliceShort(contents) catch return 0;
@@ -506,8 +495,8 @@ fn readProgress(io: std.Io, gpa: std.mem.Allocator) u32 {
     return std.fmt.parseInt(u32, trimmed, 10) catch 0;
 }
 
-fn writeProgress(io: std.Io, gpa: std.mem.Allocator, number: usize) !void {
+fn writeProgress(io: std.Io, arena: std.mem.Allocator, number: usize) !void {
-    const progress = try std.fmt.allocPrint(gpa, "{d}", .{number});
+    const progress = try std.fmt.allocPrint(arena, "{d}", .{number});
     const file = try std.Io.Dir.cwd().createFile(
         io,
         progress_filename,
@@ -693,7 +682,10 @@ const exercises = [_]Exercise{
     },
     .{
         .main_file = "028_defer2.zig",
-        .output = "(Goat) (Cat) (Dog) (Dog) (Goat) (Unknown) done.",
+        .output =
+        \\(Goat) (Cat) (Dog) (Dog) (Goat) (Unknown) done.
+        \\Answer to everything? 42
+        , // pay attention to the comma
     },
     .{
         .main_file = "029_errdefer.zig",
@@ -965,9 +957,6 @@ const exercises = [_]Exercise{
         \\Grasshopper hopped 32 meters.
         , // pay attention to the comma
     },
-
-    // Skipped because of https://github.com/ratfactor/ziglings/issues/163
-    // direct link: https://github.com/ziglang/zig/issues/6025
     .{
         .main_file = "085_async.zig",
         .output = "Current time: <timestamp>s since epoch",